'Natural' preservatives for bar soaps to guard against mold

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Garden Gives Me Joy

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Recently, I avoided carbohydrates of any type from my CP and HP soap for fear of attracting mold. However, I am missing the effect of sugars in oat milk powder but only have Phenoxyethanol (PhE) and Stabil in the house.

From what I gather; PhE is not the go-to for fighting mold. However, can I still use it with positive results if I take certain precautions? If so, what might such precautions be for CP soap? (usage rates, max usage rate for oats, etc?). ... or is it completely useless against mold?

Is there a difference in preservative performance between CP and HP? I am also wondering the same for an HP recipe.

I got the impression that Stabil is only suitable for acidic creations like lotion. So I have not even given its use in soap much thought.

Thanks.
 
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Babyshoes

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Did you have an issue with your soap going mouldy?
It's not a problem I've heard of, though I'll admit to being somewhat new to soap making, so it may just be something I've not come across as yet...
 

Dawni

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I've only encountered mold, by accident, when I had a couple of bars left somewhere I'd forgotten LOL

It's very humid here right, they were on top of kraft paper sheets, in a small wooden crate and they had sweat like crazy, enough to "melt" the soap and have the paper stuck to it. I imagine they solidified and remelted over time.

The soaps themselves didn't have mold, but the paper and the wood had mold.

Point is, soap does not need any extra ingredients to combat mold (if you do a search I recall someone explaining why). My soaps have rice, fruit purees, spices, etc.. As long as they've been incorporated properly into the soap, it's the conditions of storage you need to be careful of.
 

TheGecko

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Bar soap doesn’t need a preservative…unless you are planning on putting chunks of food in it.

May I ask what is it with you and wanting to put preservatives in everything?
 

Garden Gives Me Joy

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I live in a highly humid tropical rainforest climate. Some time back, I saw mold on top of soap that was overloaded with lots of oats, sugar and superfat. I had forgtten the used soap in a plastic bag. I also witnessed the same thing @Dawni described in that, while mold might not grow into the soap, paper and cotton wrapping that wicked moisture put mold in contact with the soap in a way that no one would want to use the soap afterwards. I have also noticed that, while the soap remains perfect, a gray ring can form on the outer perimeter of where diluted run off evaporated. It's as if the pH was no longer sufficiently high.

After those experiences, I intentionally exposed soaps to bad conditions, knowing that I can not expect everyone to follow best storage practices, even if I eliminate potential risk factors or provide adequate instructions. For instance, many people here actually have bathrooms with no windows!
 
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Interesting. Do you happen to have pictures?

Also, do you know what soda ash is? Sometimes it can be quite thick and people have confused it with mold.

The paper and fabric molding is a separate issue as both absorb moisture. It's not the soap's job to prevent the wrapping from molding.

In your experiments, did you encounter dos/rancidity from all the moisture?
 

Dawni

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I live in a highly humid tropical rainforest climate. Some time back, I saw mold on top of soap that was overloaded with lots of oats, sugar and superfat.
This is common I believe, with food stuff on top of the soap, hence why I said that any food stuff has to be incorporated IN the soap.

Also, I'm of the belief that once the soap leaves your hands in excellent condition, and it comes with proper instructions, whatever outside factors that render said soap unusable (improper storage is one major factor), is on the customer/giftee/user.

I get humidity up to near 100s here sometimes and our summers range from mid 20s to mid 30s (Celsius) and I always assume my issues with storing my soap will be the same issues customers have. My labels are probably half instructions, longer than ingredients LOL
 
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Have you tried to find the sweet spot without using a preservative? As in, using sugar at 2% of oil weight for extra bubbles? From your description of the mouldy soap being "overloaded" with sugars and other edibles, you might find that you can get away with less rather than none, and less without preservatives.

As for ideal storage, not many people do know how best to store a soap, but you left a used bar in a plastic bag! I think most people would expect a mouldy soap at that point rather than thinking that the soap is to blame. If I left a damp face cloth in a plastic bag for a while and found it mouldy, I wouldn't think that the cloth was in some way at fault for it! Especially if I lived in a climate where mould can easily grow.

In other words, I think that you're in danger on letting an abundance of caution drive you in to making unnecessary changes to your recipe
 

TheGecko

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I live in a highly humid tropical rainforest climate. Some time back, I saw mold on top of soap that was overloaded with lots of oats, sugar and superfat. I had forgtten the used soap in a plastic bag.

First of all...how do you know that it was "overloaded"? Second, it sounds like user error...sealing wet soap in a plastic bag in a humid climate. I used to live in the desert...Dad left his wet socks in a plastic grocery bag in the boat...they grew mold.

I also witnessed the same thing @Dawni described in that, while mold might not grow into the soap, paper and cotton wrapping that wicked moisture put mold in contact with the soap in a way that no one would want to use the soap afterwards. I have also noticed that, while the soap remains perfect, a gray ring can form on the outer perimeter of where diluted run off evaporated. It's as if the pH was no longer sufficiently high.

That is not the fault of the soap...that is the fault of the packaging for the climate and again, user error.

After those experiences, I intentionally exposed soaps to bad conditions, knowing that I can not expect everyone to follow best storage practices, even if I eliminate potential risk factors or provide adequate instructions. For instance, many people here actually have bathrooms with no windows!

So what are you going to do about folks who leave their soap in a puddle of water? Or having streaming sunlight in their bathrooms? Or who don't use their exhaust fans? And how are you going to account for all the different climates and changing seasons across the US alone?

The simple fact is...you can't. And there is no expectation that you should. Many years ago, I did some side work for mineral makeup and natural skin care company...handled a lot of "complaints". 99% of time it was 'customer error'...not closing lids, storing the product on the window sill, soaking brushes in water, dipping wet brushes in the pots...doing all the things they are told NOT to do.

Some things I can control based on what is 'reasonable', some things I cannot. Like adding a preservative to a salt or sugar scrub, but not adding it to bath salts...it is reasonable to assume that folks will dip wet fingers into a scrub, but not into bath salts. The only issue I have had with bath salts is people not closing the lid tightly and so the scent fades. NOTHING I can do about that.
 

TheGecko

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Pretty sure preservatives won't prevent mold, they are to stop bacteria and other germs

It depends on the product and the preservative. The thing of it is, nothing is absolute and the use thereof is based on what is normal, not extraordinary...like sealing a wet bar of soap in a plastic bag in a hot and humid environment. Even in a desert climate, you're going to have issues with that soap.
 
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@Garden Gives Me Joy
Sorbic acid does occur naturally (e. g. in cooked rowanberries), and (as potassium/sodium sorbate) is even kind of a soap itself: alkali salt of a straight-carbon-chain carboxylic acid.
It is effective against mould, but only as the free acid (i. e. not so much in alkaline environments).

IMHO, this is about the best compromise when you want to avoid the arsenal of chemical industry, but still want to do something about mould for the peace of your mind.


ETA: I'm now wondering if nobody has done a soap with rowanberry purée before? … and if it's just for the colour
 
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Good find! (Nobody can complain she is too chatty, and I LOVE Erik Satie). But I find it a bit anticlimatic how little of the colour of the “rowanberry tea” survives, and that she has to resort to madder root powder. AFAIK the pigments in rowanberries are mostly carotenoids, i. e. oil-soluble (like tomato, annatto, carrots) hence it's kind of pointless to make an aqueous extract from them. She also hasn't cooked the berries long enough, they would just decompose into a nice and thick mash all by themselves if cooked a bit longer.
I don't complain at all. I'm inclined to HP, I love circular column mould soaps, and I admire her steady hand at beveling these. It's just that, if I had undertaken a “rowan soap”, it'd look a bit differently – but that's me.

And it's a very loose tangent to the topic of this thread anyway. 🤐
 
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Not that sure. Carotene pigments (red palm, annatto, paprika) have a good track of being rather insensitive to lye. I rather blame the unsuitable extraction medium (water) for the weak colour strength. I don't know if you have ever messed around with rowanberries, if you want you can get a LOT more of a stains to clean up, than she did.
 

TheGecko

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Not that sure. Carotene pigments (red palm, annatto, paprika) have a good track of being rather insensitive to lye. I rather blame the unsuitable extraction medium (water) for the weak colour strength. I don't know if you have ever messed around with rowanberries, if you want you can get a LOT more of a stains to clean up, than she did.

Nope...no berries here. Outside of base oils/butters I have used: Goat Milk (evap, store and straight from the goat), Coconut Milk and Distilled Water; I have used EOs and FOs; colorants have been Micas, Pigments, Clays and Oxides; additives have been to date...Sodium Lactate, sugar, salt and walnut shells.

I do have some other stuff to try: Goat Milk Powder, Tussah Silk, Colloidal Oatmeal, Chamomile Powder, Calendula Flowers, Plantain Leaf Powder, Red Palm Oil, Vanilla Bean Powder and some Hibiscus Flower Powder.

I do have an interest in trying some 'natural' colorants but some of it's fairly expensive...which is pretty stupid considering how much I paid for that tiny little amount of Vanilla Bean Powder, but in my defense...it package looked a lot bigger. LOL
 
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